Caption: Euglena protozoan. Differential interference contrast micrograph of the flagellate protozoan Euglena spirogyra. This freshwater single-celled organism can either obtain energy from sunlight, via photosynthesis, or by absorbing chemicals from its surroundings.
A sensory organ, known as the eye spot, or stigma (red), is able to perceive the intensity of light.
Magnification: x225 when printed at 10 centimetres wide.